The subject matter of the present invention is a composition for bleaching or decolorizing hair, especially human hair, made from two components.
Oxidizing preparations are usually used for bleaching of hair. These oxidizing preparations are made by dissolving a so-called bleaching powder (powder mixture comprising an alkali salt and inorganic per-salt, such as sodium or ammonium persulfate) in an aqueous hydrogen peroxide solution.
The use of this type of bleaching powder, which is necessarily composed of several ingredients, however results in several disadvantages. Thus frequently during transportation or storage different powder ingredients separate because of the use of ingredients with different densities, since the heavier powder ingredient collects in the lower part and the lighter powder ingredient in the upper part. This separation has the consequence that the same powder amounts can have different chemical compositions and thus a different bleaching effect depending on the location from which they are obtained.
In order to counter this separation effect, it is necessary to shake the powder prior to taking a portion of it for bleaching, but the user usually does not do this.
A separation of ingredients can also be prevented by using powder mixtures with comparatively very much smaller grain size. This however has the disadvantage that this type of powder mixture--especially on opening of the container during removal of powder or mixture with hydrogen peroxide--is strongly inclined to produce dust, which can lead to an irritation of the lungs. Furthermore this type of powder mixture has a comparatively large surface area because of its reduced grain size, whereby uptake of moisture on opening and closing of the container and thus a reduction of the bleaching effect is promoted, because of the deactivation of the acid carrier material.
The preparation of the ready-to-use mixture takes place by stirring the components in a vessel or bowl, among other things by mixing in a shaking flask, whereby particularly the shaking is connected with a troublesome dust production on filling the components into the shaking flask.
Already numerous attempts have been made to solve this problem.
Thus for example in German Patent Application DE-OS 40 26 235, instead of a bleaching powder, a mixture comprising a granulate of inorganic persulfate and a granulate of the remaining ingredients of the bleaching powder is suggested for use. Because of that the problem of dust production is eliminated. The problem of separation however cannot be solved in this way, since it is exceptionally difficult from an engineering standpoint, to make an individual granulate with identical and constant grain size or batch weight. Furthermore because of the differing solubilities of the two granulates, the bleaching action can be impaired. Furthermore from an economical standpoint it appears to be of minor significance to make a mixture of several granulates instead of a single granulate.
In German Patent Application DE-AS 20 23 922 it is recommended to use a granulate instead of a powder. This granulate is made by spraying all the required ingredients to make the bleaching powder with an aqueous, alcoholic or aqueous-alcoholic polymer solution in a suitable mixer.
During the granulating process however there are comparatively large ammonia losses, whereby the bleaching effect of the granulate is impaired. These ammonia losses would be compensated by increasing of the ammonium salt proportion in the powder used and/or by addition of ammonia to the polymer solution. Since the ammonia loss fluctuates comparatively greatly in this granulation process due to process conditions, it is not possible to make a granulate with a constant chemical composition with this process.
Furthermore with this bleaching composition freedom from dust production is not completely guaranteed, since fine dust is produced by friction between the granulate particles, e.g. during transportation.
Because of the poor solubility of the granulate use of this type of bleaching granulate in a shaking flask is not possible.
In European Patent Application EP-PS 0 560 088 a powdery composition for bleaching hair is described, in which an oil or flowing wax is added to prevent dust formation. However here too complete freedom from dust production cannot be achieved. Also a deactivation of the acid material carrier occurs because of the water content of the powdery raw materials and the compact powder form required by the oil addition, whereby the product is unstable and its bleaching action is lost.
Furthermore this type of bleaching composition because of its specific gravity and its hydrophobic character is unsuitable for use in an applicator bottle, since the powder in the hydrogen peroxide solution is not sufficiently wetted after sinking, whereby an inhomogeneous mixing with a proportion of undissolved powder results with the result that the outlet orifice of the applicator bottle is plugged. The results of addition of surfactants to improve solubilities is similarly problematic, since the storability of the powder is thereby impaired.